<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body class="c1">
    <div class="c1">hello div <b id="b1">!</b></div>

    <input type="text" name="username" id="" />
    <script>
      console.log(document.getElementsByClassName("c1"));
      console.log(document.getElementsByName("username"));
      console.log(document.getElementsByTagName("div"));
    </script>
  </body>
</html>
